Electrode and Secondary Battery Including Same

The present application claims priority to and the benefit of Korean Application No. 10-2024-0082813, filed on Jun. 25, 2024, in the Korean Intellectual Property Office, the entire disclosure of which is incorporated by reference herein.

The present disclosure relates to an electrode and a secondary battery including the same.

Unlike primary batteries that are not designed to be (re) charged, secondary (or rechargeable) batteries are batteries that are designed to be discharged and recharged. Low-capacity secondary batteries are used in portable, small electronic devices, such as smart phones, feature phones, notebook computers, digital cameras, and camcorders, while large-capacity secondary batteries are widely used as power sources for driving motors in hybrid vehicles and electric vehicles and for storing power (e.g., home and/or utility scale power storage). A secondary battery generally includes an electrode assembly composed of a positive electrode and a negative electrode, a case accommodating the same, and electrode terminals connected to the electrode assembly.

The positive electrode and negative electrode may be manufactured by coating a substrate with a composite layer. During the manufacturing process, the composite layer may have a low-strength region (e.g., a region having strength or durability that is lower than another region of the composite layer). During the life cycle of a secondary battery, the electrodes may repeatedly contract and expand, and cracks may be formed in the low-strength region. The cracks may reduce the life of the secondary battery.

The above information disclosed in this Background section is for enhancement of understanding of the background of the present disclosure, and therefore, it may contain information that does not constitute related (or prior) art.

Embodiments of the present disclosure are directed to an electrode and a secondary battery including the same that are configured to address the problems described above.

These and other aspects and features of the present disclosure will be described in or will be apparent from the following description of embodiments of the present disclosure.

According to one or more embodiments of the present disclosure, an electrode includes: a substrate made of a metallic material; a first composite layer coated on a portion of a first surface of the substrate to form a first uncoated portion on a first end of the first surface; a second composite layer coated on a portion of a second surface of the substrate to form a second uncoated portion on a second end of the second surface; and a reinforcing film attached to a third end portion of at least one of the first composite layer or the second composite layer.

In an embodiment, a first length of the first composite layer may be greater than a second length of the second composite layer, and the reinforcing film may be attached to the third end portion of the second composite layer and the second uncoated portion.

In an embodiment, the reinforcing film may include: a first portion covering a first region from the third end portion of the second composite layer to a portion of the second composite layer; and a second portion covering a second region from the third end portion of the second composite layer to a portion of the second uncoated portion.

In an embodiment, a third length of the first portion may be greater than a fourth length from the third end portion of the second composite layer to a point of the second composite layer to which sheer stress greater than a threshold sheer stress may be applied during rolling of the second composite layer.

In an embodiment, a third length of the first portion may be greater than a fourth length from the third end portion of the second composite layer to a point of the second composite layer where a fatigue failure occurs first.

In an embodiment, a third length of the first portion may be in a range from approximately 0.6 mm to approximately 2.0 mm from the end portion of the second composite layer.

In an embodiment, the second surface of the substrate may include a chargeable region and non-chargeable region, and a third length of the reinforcing film may be set to cover the non-chargeable region excluding the chargeable region.

In an embodiment, a thickness of the reinforcing film ranges from approximately 15 μm to approximately 50 μm.

In an embodiment, a width of the reinforcing film may be equal to or smaller than a width of the substrate.

In an embodiment, the reinforcing film may include a thermal fusion film, and may be attached via heat and pressure.

In an embodiment, the reinforcing film may include a heat-resistant film including an adhesive layer, and may be attached by the adhesive layer.

In an embodiment, the second composite layer may be coated on the second surface of the substrate after the first composite layer may be coated on first surface of the substrate.

In an embodiment, a third length of the second uncoated portion in a longitudinal direction of the substrate may be greater than a fourth length of the first uncoated portion in the longitudinal direction of the substrate.

In an embodiment, a third length of the second uncoated portion in a longitudinal direction of the substrate may be equal to a fourth length of the first uncoated portion in the longitudinal direction of the substrate.

In an embodiment, a first portion of the second composite layer may be positioned at a center of the electrode and a second portion of the second composite layer may be positioned in a periphery of the electrode.

In an embodiment, each of the first composite layer and the second composite layer may include a positive electrode, and the substrate may include a positive electrode substrate.

According to one or more embodiments of the present disclosure, a secondary battery includes: an electrode assembly including a first electrode, a separator, and a second electrode; a case configured to accommodate the electrode assembly; and a cap assembly coupled to an open area of the case to seal the case. The first electrode may include: a substrate made of a metallic material; a first composite layer coated on a portion of a first surface of the substrate to form a first uncoated portion on a first end of the first surface; a second composite layer coated on a portion of a second surface of the substrate to form a second uncoated portion on a second end of the second surface; and a reinforcing film attached to a third end portion of at least one of the first composite layer or the second composite layer.

In an embodiment, in a wound state of the first electrode, first portions of the first composite layer and the second composite layer are positioned at a center of the electrode assembly, and second portions of the first composite layer and the second composite layer are positioned in a periphery of the electrode assembly.

In an embodiment, the second composite layer may be positioned to face the second electrode, and the reinforcing film may be attached to the third end portion of the second composite layer and to the second uncoated portion.

In an embodiment, the first composite layer and the second composite layer may include a positive electrode active material, and the substrate may include a positive electrode substrate, where the first electrode functions as a positive electrode.

According to some embodiments of the present disclosure, crack formation may be prevented or reduced by attaching a reinforcing film to a low-strength region in a composite layer.

However, aspects and features of the present disclosure are not limited to those described above, and other aspects and features not mentioned will be clearly understood by a person skilled in the art from the detailed description, described below.

Hereinafter, embodiments of the present disclosure will be described, in detail, with reference to the accompanying drawings. The terms or words used in the present specification and claims are not to be limitedly interpreted as general or dictionary meanings and should be interpreted as meanings and concepts that are consistent with the technical idea of the present disclosure on the basis of the principle that an inventor can be his/her own lexicographer to appropriately define concepts of terms to describe his/her invention in the best way.

The embodiments described in this specification and the configurations shown in the drawings are only some of the embodiments of the present disclosure and do not represent all of the technical spirit, aspects, and features of the present disclosure. Accordingly, it should be understood that there may be various equivalents and modifications that can replace or modify the embodiments described herein at the time of filing this application.

It will be understood that when an element or layer is referred to as being “on,” “connected to,” or “coupled to” another element or layer, it may be directly on, connected, or coupled to the other element or layer or one or more intervening elements or layers may also be present. When an element or layer is referred to as being “directly on,” “directly connected to,” or “directly coupled to” another element or layer, there are no intervening elements or layers present. For example, when a first element is described as being “coupled” or “connected” to a second element, the first element may be directly coupled or connected to the second element or the first element may be indirectly coupled or connected to the second element via one or more intervening elements.

In the figures, dimensions of the various elements, layers, etc. may be exaggerated for clarity of illustration. The same reference numerals designate the same elements. As used herein, the term “and/or” includes any and all combinations of one or more of the associated listed items. Further, the use of “may” when describing embodiments of the present disclosure relates to “one or more embodiments of the present disclosure.” Expressions, such as “at least one of” and “any one of,” when preceding a list of elements, modify the entire list of elements and do not modify the individual elements of the list. When phrases such as “at least one of A, B and C, “at least one of A, B or C,” “at least one selected from a group of A, B and C,” or “at least one selected from among A, B and C” are used to designate a list of elements A, B and C, the phrase may refer to any and all suitable combinations or a subset of A, B and C, such as A, B, C, A and B, A and C, B and C, or A and B and C. As used herein, the terms “use,” “using,” and “used” may be considered synonymous with the terms “utilize,” “utilizing,” and “utilized,” respectively. As used herein, the terms “substantially,” “about,” and similar terms are used as terms of approximation and not as terms of degree, and are intended to account for the inherent variations in measured or calculated values that would be recognized by those of ordinary skill in the art.

It will be understood that, although the terms first, second, third, etc. may be used herein to describe various elements, components, regions, layers, and/or sections, these elements, components, regions, layers, and/or sections should not be limited by these terms. These terms are used to distinguish one element, component, region, layer, or section from another element, component, region, layer, or section. Thus, a first element, component, region, layer, or section discussed below could be termed a second element, component, region, layer, or section without departing from the teachings of example embodiments.

Spatially relative terms, such as “beneath,” “below,” “lower,” “above,” “upper,” and the like, may be used herein for ease of description to describe one element or feature's relationship to another element(s) or feature(s) as illustrated in the figures. It will be understood that the spatially relative terms are intended to encompass different orientations of the device in use or operation in addition to the orientation depicted in the figures. For example, if the device in the figures is turned over, elements described as “below” or “beneath” other elements or features would then be oriented “above” or “over” the other elements or features. Thus, the term “below” may encompass both an orientation of above and below. The device may be otherwise oriented (rotated 90 degrees or at other orientations), and the spatially relative descriptors used herein should be interpreted accordingly.

The terminology used herein is for the purpose of describing embodiments of the present disclosure and is not intended to be limiting of the present disclosure. As used herein, the singular forms “a” and “an” are intended to include the plural forms as well, unless the context clearly indicates otherwise. It will be further understood that the terms “includes,” “including,” “comprises,” and/or “comprising,” when used in this specification, specify the presence of stated features, integers, steps, operations, elements, and/or components but do not preclude the presence or addition of one or more other features, integers, steps, operations, elements, components, and/or groups thereof.

Also, any numerical range disclosed and/or recited herein is intended to include all sub-ranges of the same numerical precision subsumed within the recited range. For example, a range of “1.0 to 10.0” is intended to include all subranges between (and including) the recited minimum value of 1.0 and the recited maximum value of 10.0, that is, having a minimum value equal to or greater than 1.0 and a maximum value equal to or less than 10.0, such as, for example, 2.4 to 7.6. Any maximum numerical limitation recited herein is intended to include all lower numerical limitations subsumed therein, and any minimum numerical limitation recited in this specification is intended to include all higher numerical limitations subsumed therein. Accordingly, Applicant reserves the right to amend this specification, including the claims, to expressly recite any sub-range subsumed within the ranges expressly recited herein. All such ranges are intended to be inherently described in this specification such that amending to expressly recite any such subranges would comply with the requirements of 35 U.S.C. § 112(a) and 35 U.S.C. § 132(a).

References to two compared elements, features, etc. as being “the same” may mean that they are “substantially the same”. Thus, the phrase “substantially the same” may include a case having a deviation that is considered low in the art, for example, a deviation of 5% or less. In addition, when a certain parameter is referred to as being uniform in a given region, it may mean that it is uniform in terms of an average.

Throughout the specification, unless otherwise stated, each element may be singular or plural.

Arranging an arbitrary element “above (or below)” or “on (under)” another element may mean that the arbitrary element may be disposed in contact with the upper (or lower) surface of the element, and another element may also be interposed between the element and the arbitrary element disposed on (or under) the element.

In addition, it will be understood that when a component is referred to as being “linked,” “coupled,” or “connected” to another component, the elements may be directly “coupled,” “linked” or “connected” to each other, or another component may be “interposed” between the components”.

Throughout the specification, when “A and/or B” is stated, it means A, B or A and B, unless otherwise stated. That is, “and/or” includes any or all combinations of a plurality of items enumerated. When “C to D” is stated, it means C or more and D or less, unless otherwise specified.

illustrates an example of an electrode according to embodiments of the present disclosure,illustrates an example in which a reinforcing film is attached to an electrode according to embodiments of the present disclosure,illustrates an example of a region of an electrode according to embodiments of the present disclosure in which cracks are formed,illustrates an example of an electrode according to embodiments of the present disclosure to which a reinforcing film is attached, andillustrates an example of a reinforcing film according to embodiments of the present disclosure.

Referring to, an electrodeaccording to embodiments of the present disclosure includes: a substrateformed of a metallic material; a first composite layercoated on a portion of a first surfaceof the substrateto form a first uncoated portionon an end of the first surfaceof the substrate; a second composite layercoated on a portion of a second surfaceof the substrateto form a second uncoated portionon an end of the second surfaceof the substrate; and a reinforcing filmattached to an end of at least one of the first composite layeror the second composite layer. Herein, the composite layers may also be referred to as active material layers.

The substrateis a collector (or current collector) made of a metallic material, which may be constructed in the form of a plate (e.g., a thin or relatively thin plate) or a metal film. In an embodiment, the substratemay be made of an aluminum foil or copper foil.

The first composite layermay be formed on the first surfaceof the substrate, and the second composite layermay be formed on the second surfaceof the substrate. The first composite layerand the second composite layermay be manufactured by applying electrode composites each including a binder and a coating material to the surfaces of the substrate, followed by drying and rolling.

According to some embodiments, the electrode composites of the first composite layerand the second composite layermay include the same components. For example, the electrode composites may include a positive electrode active material plus a binder and a coating material. For example, the electrode composites may include a negative electrode active material plus a binder and a coating material. In some embodiments, the electrode composites of the first composite layerand the second composite layermay be different. For example, the electrode composite of the first composite layermay include a positive electrode active material plus a binder and a coating material, and the electrode composite forming the second composite layermay include a negative electrode active material plus a binder and a coating material, or vice versa.

In an embodiment, as shown in, the length of the first composite layermay be greater than the length of the second composite layer. In other words, the length of the second uncoated portionin the longitudinal direction of the substratemay be greater than the length of the first uncoated portionin the longitudinal direction of the substrate.

After the first composite layeris first formed on the first surfaceof the substrateby coating, the second composite layermay be formed on the second surfaceof the substrateby coating. In an embodiment, an electrode composite may be applied to the first surfaceof the substrate, followed by drying, and then a rolling process may be performed to flatten the first composite layer. In this case, the rolling may start at an end portionof the first composite layerand end at a start portionof the first composite layer. In some embodiments, an electrode composite may be applied to the second surfaceof the substrate, followed by drying, and then a rolling process may be performed to flatten the second composite layer. In this case, the rolling may start at an end portionof the second composite layerand end at a start portionof the second composite layer. In an embodiment where the substrateis wound to form an electrode assembly, the start portionof the second composite layermay be disposed at the center and the end portionof the second composite layermay be disposed in the periphery.

In an embodiment, in the process of forming the first composite layeron the substrate, applying the electrode composite to the second surfaceof the substrate, and drying the electrode composite, followed by rolling, a maximum or substantially maximum shear stress (collectively referenced as maximum shear stress) may be applied to a region R of the second composite layerproximate to the end portionof the second composite layer. In some embodiments, substantially maximum sheer stress may include sheer strength that is greater than a threshold shear stress. The region R to which the maximum shear stress is applied may be a region where the second composite layeris damaged and a fatigue failure may occur first. In some embodiments, the electrodes may repeatedly contract and expand during the life cycle of the secondary battery, and fatigue failure may occur (e.g., rapidly occur) in the region R where the maximum shear stress is applied to the second composite layer, which may lead to a reduction of the life of the secondary battery.